/**
 * Copyright 2010 Eric Taix Licensed under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with the
 * License. You may obtain a copy of the License at
 * http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable
 * law or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the specific
 * language governing permissions and limitations under the License.
 */
package org.jared.synodroid.common;

/**
 * An utility class which displays a EULA Big thanks to Konstantin
 * (http://androiddevstudio.com/) who's created a tutorial for this class
 * and saved me a lot of time.
 * 
 * @author Eric Taix (eric.taix at gmail.com)
 */

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.SharedPreferences;

import java.io.IOException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.Closeable;

import org.jared.synodroid.ds.R;

/**
 * Displays an EULA ("End User License Agreement") that the user has to
 * accept before using the application. Your application should call
 * {@link Eula#show(android.app.Activity)} in the onCreate() method of the
 * first activity. If the user accepts the EULA, it will never be shown
 * again. If the user refuses, {@link android.app.Activity#finish()} is
 * invoked on your activity.
 */
public class Eula {
  private static final String ASSET_EULA = "EULA";
  private static final String PREFERENCE_EULA_ACCEPTED = "eula.accepted";
  private static final String PREFERENCES_EULA = "eula";

  /**
   * callback to let the activity know when the user has accepted the EULA.
   */
  public interface OnEulaAgreedTo {

    /**
     * Called when the user has accepted the eula and the dialog closes.
     */
    void onEulaAgreedTo();
  }

  /**
   * Displays the EULA if necessary. This method should be called from the
   * onCreate() method of your main Activity.
   * 
   * @param activity The Activity to finish if the user rejects the EULA.
   * @return Whether the user has agreed already.
   */
  public static boolean show(final Activity activity, boolean forceToShow) {
    final SharedPreferences preferences = activity.getSharedPreferences(PREFERENCES_EULA, Activity.MODE_PRIVATE);
    if (!preferences.getBoolean(PREFERENCE_EULA_ACCEPTED, false) || forceToShow) {
      final AlertDialog.Builder builder = new AlertDialog.Builder(activity);
      builder.setTitle(R.string.eula_title);
      builder.setCancelable(!forceToShow);
      if (!forceToShow){
	      builder.setPositiveButton(R.string.eula_accept, new DialogInterface.OnClickListener() {
	        public void onClick(DialogInterface dialog, int which) {
	          accept(preferences);
	          if (activity instanceof OnEulaAgreedTo) {
	            ((OnEulaAgreedTo) activity).onEulaAgreedTo();
	          }
	        }
	      });
	      builder.setNegativeButton(R.string.eula_refuse, new DialogInterface.OnClickListener() {
	        public void onClick(DialogInterface dialog, int which) {
	          refuse(preferences,activity);
	        }
	      });
	      builder.setOnCancelListener(new DialogInterface.OnCancelListener() {
	        public void onCancel(DialogInterface dialog) {
	          refuse(preferences,activity);
	        }
	      });
      }
      else{
    	  builder.setPositiveButton(R.string.eula_hide, new DialogInterface.OnClickListener() {
  	        public void onClick(DialogInterface dialog, int which) {
  	          //DO NOTHING JUST HIDE IT ...
  	        }
  	      });
    	  builder.setOnCancelListener(new DialogInterface.OnCancelListener() {
  	        public void onCancel(DialogInterface dialog) {
  	        //DO NOTHING JUST HIDE IT ...
  	        }
  	      });
      }
      builder.setMessage(readEula(activity));
      builder.create().show();
      return false;
    }
    return true;
  }

  private static void accept(SharedPreferences preferences) {
    preferences.edit().putBoolean(PREFERENCE_EULA_ACCEPTED, true).commit();
  }

  private static void refuse(SharedPreferences preferences, Activity activity) {
    preferences.edit().putBoolean(PREFERENCE_EULA_ACCEPTED, false).commit();
    activity.finish();
  }

  private static CharSequence readEula(Activity activity) {
    BufferedReader in = null;
    try {
      in = new BufferedReader(new InputStreamReader(activity.getAssets().open(ASSET_EULA)));
      String line;
      StringBuilder buffer = new StringBuilder();
      while ((line = in.readLine()) != null)
        buffer.append(line).append('\n');
      return buffer;
    }
    catch(IOException e) {
      return "";
    }
    finally {
      closeStream(in);
    }
  }

  /**
   * Closes the specified stream.
   * 
   * @param stream The stream to close.
   */
  private static void closeStream(Closeable stream) {
    if (stream != null) {
      try {
        stream.close();
      }
      catch(IOException e) {
        // Ignore
      }
    }
  }
}
